This application claims priority of DE 198 58 435.0, filed Dec. 17, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a cover-skin web structure for use in flow profiles, in particular aerofoils or their components, comprising a cover skin on the pressure side and a cover skin on the suction side, connected by webs aligned in the direction of the span. The webs have one or several web cutouts essentially extending from the cover skin on the suction side to the cover skin on the pressure side.
In many cases, modern wing profiles are of modular design so as to ensure good and fast access to the individual areas of the structure. Thus structures are used whose cover skins on the suction side or on the pressure side are connected via webs aligned in the direction of the span. The cover-skin web structure is pushed over the ribs attached to the structural parts, with the ribs being aligned in the airflow direction.
DE 196 432 22 A1 shows a known cover-skin web structure made of fiber reinforced material for the landing flap of an aerofoil. A cover skin on the suction side and on the pressure side is connected by webs aligned in the span direction. The webs comprise web cutouts, offset in the direction of the span. Ribs aligned in the direction of airflow and attached to structural parts engage the web cutouts so as to ensure stabilization of the structure under aerodynamic loads in the airflow direction. This structure is constructed in a modular way, is of lightweight construction due to its production from fiber reinforced material and can be bent with little force if a profile change is desired.
This structure has the disadvantage that the fiber reinforced material of the webs, in the area of the web cutouts, does not stand up to the high aerodynamic loads which are introduced via the webs into the ribs. Considerable material extension can be achieved with fiber reinforced materials if the material is exposed to the loads along the direction of the fibers. Because such a fiber geometry cannot be realized in the fringe area of the web cutouts to the ribs, however, the achievable elongation is insufficient to transfer the aerodynamic loads in the fringe area from the webs to the ribs without damaging the fiber reinforced material.